Crossodonthina bidentata, Luo, Yongzheng & Chen, Jian-Xiu, 2009

Luo, Yongzheng & Chen, Jian-Xiu, 2009, A new species of the genus Crossodonthina (Collembola: Neanuridae: Lobellini) from China, Zootaxa 2121, pp. 57-63 : 58-62

publication ID	https://doi.org/ 10.5281/zenodo.188101
DOI	https://doi.org/10.5281/zenodo.5619318
persistent identifier	https://treatment.plazi.org/id/A51987AE-FFE7-820B-FF41-D709B0B1F954
treatment provided by	Plazi
scientific name	Crossodonthina bidentata
status	sp. nov.

Treatment

Crossodonthina bidentata , sp. nov.

Figures 1–14 View FIGURES 1 – 7 View FIGURES 8 – 14 , Tables 1–3 View TABLE 1

Type material. Holotype: female, China, Zhejiang Province, Tianmu Mountain (alt. 1200–1500m, 30o 18’–20’ N, 119o 26’–28’ E), 14-IV-05, collection number C9248, collected by Chen Jian-xiu, Luo Yongzheng and other students. Paratypes: 11 females, 5 males, and 2 juveniles; 1 female, alt. 339m, 12-IV-05, collection number C9242; 1 female and 1 male, alt. 340–700m, 15-IV-05, collection number C9245; 8 females and 1 juvenile besides 6 specimens in alcohol, alt. 1020–1220m, 14-IV-05, collection number C9249; other data as holotype. All deposited in the School of Life Science, Nanjing University, China.

Description. Body length. Up to 2.2mm.

Color. Red while living and wholly white in alcohol.

Head. Head hypognathous. Eyes 2+2, unpigmented and separated from each other ( Fig. 1 View FIGURES 1 – 7 ). Ratio of antenna to head as 1:1.3–1.9. Ant. III & IV dorsally fused. Length ratio of antennal segments as I: II: (III + IV) = 1: 0.7–0.9: 1.6–2.4. Ant. I and II respectively with 9 and 11 setae. Ant. III with 18 common setae. Ant. III organ consisting of 5 sensory setae, including sgd, sgv, ms and 2 strongly curved rods in separate pits. Ant IV apical bulb trilobed, dorsal chaetotaxy as 8S, i, 12 mou and or ( Figs. 3, 4 & 5 View FIGURES 1 – 7 ). Buccal cone weakly developed. Labrum truncate and granulated, setal formula as 2/5, 2 ( Fig. 6 View FIGURES 1 – 7 ). Labium with 2 x and 3 setae (A, C, D) on proximal part of palp, 4 (E, F, G, f) on submentum and 4 (b, c, d, e) on mentum (after Massoud 1967) ( Fig. 7 View FIGURES 1 – 7 ). Mandible elongate, consisting of 2 subequal prominent basal teeth and 3 curved rami. Upper ramus small, feather-like and densely with thin and simple (rarely bifurcated) setae; mid ramus as flagellum, subequal to upper ramus in length; lower ramus large, 3–4 times as long as upper two, having 2 densely fringed lamellae, marginal setae on lamellae bi- to multi-furcated (rarely simple), setae thin on upper (dorsal) lamella and thick on lower (ventral) lamella ( Fig. 8 View FIGURES 8 – 14 ). Maxillary head consisting of 2 stylets, inner one with 2 minute apical teeth, outer one branched apically ( Fig. 9 View FIGURES 8 – 14 ).

Cephalic tubercles and chaetotaxy. Dorsal central area with 6 separate tubercles and 21 setae; tubercle Cl with 4 setae (2F, 2G), 2An each with 4 setae (B, C, D, E), Fr with 3 setae ( O, 2A), and 2Oc each with 3 setae (Oca, Ocm, Ocp). Dorsal posterior area with 4 separate tubercles and 8 setae totally; 2 Di each with 1 seta ( Di 1) and 2 De each with 3 setae ( De 1, De 2, Di 2). Dorsal lateral area with 3 tubercles fused and 15 (16) setae totally; Dl, L and So respectively represented by 6, 4 and 5(6) setae ( Fig. 1 View FIGURES 1 – 7 and Table 1 View TABLE 1 ). Ventral side respectively with 6 and 8 setae in internal (Vi) and external (Ve) areas ( Fig. 7 View FIGURES 1 – 7 ).

Tubercle Number of setae Types of setae Names of setae Cl 2 M F, F

Body tubercles and chaetotaxy. Tubercles rounded. Th. I with 3+3 tubercles ( Di, De, Dl). Th. II-Abd. IV respectively with 4+4 tubercles ( Di, De, Dl, L). Abd. V with 5 tubercles; 2 Di fused, De and Dl fused, 2L separate and ventrally situated. Abd. VI with 1+1 tubercles. Sensory seta (s) and sensory microseta (ms) formula as 2+ms, 2/1, 1, 1, 1, 1 ( Figs 1 & 2 View FIGURES 1 – 7 and Table 2). Each anal valve (Av) with 3 microsetae in both sexes. Genital plate with 12–25 and 31–53 setae respectively in female and male ( Fig. 14 View FIGURES 8 – 14 ).

Appendices. Chaetotaxy of legs, ventral tube and furcular remnant shown in Table 2. Tibiotarsi I–III respectively with 19, 19, 18 setae. Among setae on each femur and tibiotarsus, 1 ventral seta particularly large. Unguis ventrally with 1 inner tooth, basal granules and medial transverse striae. Unguiculus and tenent hair absent ( Fig. 13 View FIGURES 8 – 14 ). Ventral tube anteriorly with 1+1 proximal and 3+3 distal setae ( Fig. 11 View FIGURES 8 – 14 ). Furcula reduced to elliptic area with 5 (6) setae ( Fig. 12 View FIGURES 8 – 14 ).

Etymology. The name of the new species is derived from Latin bi- and dent- for two teeth because of the two prominent basal teeth on mandible.

Terga Legs

Di De Dl L Scx Cx Tr Fe T Th. I M M+me M -- 0 3 6 13 19 Th. II M+me+mi M+me+mi+s M+2me+s+ms M+2me 2 7 6 12 19 Th. III M+me+mi M+me+ 2mi +s M+2me+s M+2me 2 8 6 11 18 Terga Sterna

Abd. I M+me M+2me+s M+me M+2me VT: 4

Abd. II M+me M+2me+s M+me M+2me Ve: 5

Abd. III M+me M+2me+s M+me M+2me Ve: 4(5) Fu: 5(6) Abd. IV M+me M+me+s M+2me 5M+me Ve: 10 (9) Vl: 5(4) Abd. V 2 (M+2me) ----------- 2M+2me+s ----------- 2M+2me Ag: 3 Vl: 1 Abd. VI ---------------------------- 4M+3me ----------------------------- Ve: 14 (13)

Ecology. Found in leaf litter in deciduous forest.

Remarks. The new species is unique in the genus in having tubercles Di fused on Abd. V and in the unusual structure of mandibles and maxillae. The mandible consists of 2 subequal prominent basal teeth, 1 whip-like ramus and 2 densely fringed rami of quite different sizes. The maxilla consists of 2 stylets, inner one with 2 minute apical teeth, outer one branched apically. Additionally, the labral chaetotaxy of the new species is /5, 2; however, it is / 2, 2 in most species of Lobellini including the genus Crossodonthina . There are 5(6) setae present on the furcular remnant in the new species, rather than 6 as in C. hainana , 4 as in C. montana and 3 as in most species in the genus, such as C. nipponica (see Yosii 1995), C. koreana , C. formosana , C. alatoserrata , C. tridentiens and C. tiantongshana . The macrosetae (M) are acuminate, very slightly ciliate on distal half and wingless but smooth in C. nipponica , C. koreana , C. formosana and C. hainana , and winged in C. alatoserrata and C. tridentiens . The new species is the third one with 2+2 eyes in the genus. It is similar to the 2+2-eyed Chinese species, C. montana and C. hainana , in the Ant. IV with 8 sensory setae, unguis with 1 inner tooth and ventral tube with 4+4 setae, and the body dorsal chaetotaxy. However, it is easily distinguished from the latter two by the number of setae on cephalic tubercles Oc, as well as the Di tubercles fused on Abd. V, the structure of mandibles and maxillae, the number of setae on furcular remnant and the morphological feature of macrosetae (M) ( Table 3 View TABLE 3 ).